Fix install command
Fix install command

When a relative directory is given as the value to the DESTINATION argument of the cmake [`install`](https://cmake.org/cmake/help/v3.0/command/install.html) command, it is already treated as being relative to `CMAKE_INSTALL_PREFIX`.  When we redundantly specify it, then the PACKAGE operation can fail if the user specified `CMAKE_INSTALL_PREFIX` during configuration because it is interpreted to an absolute path at configuration time and is not resolved again when it has to be overridden at package time.

codemercenary/autowiring,leapmotion/autowiring,codemercenary/autowiring,codemercenary/autowiring,codemercenary/autowiring,leapmotion/autowiring,leapmotion/autowiring,leapmotion/autowiring,leapmotion/autowiring,codemercenary/autowiring,codemercenary/autowiring,leapmotion/autowiring